Electric-circuit interrupter.



F. W. HARRIS.

ELECTRIC cmcurr INTERBUPTER.

APPLICATION FILED MAY 6, 1907.

' Patented July 12,1910.

. INVENTOR ATTORNEY N/ 0 w m m m m 5 WM 7 4 a 0 m WM WM fi w W. 4 M w m 0 m 5 c I- 1 w I w v/. 4 4 O 6 1 9N 3 y 3 4 3 Z E m z 8 G a. W n n z 7 a i N 8 S E W W m m IH W m w W 5 To all whom it may concern:

Be it known that I, Foul) W. HARRIs,a citizen of the United States, and a resident of Wilkinshurg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Electric- Circuit Interrupters, of which the following is a specification.

My invention relates to automatic interrupters for electric circuits, and it has for its object to provide an improved device of this character that shall be adapted to open thecircuit in which it is connected, underpredetermined conditions ot load and temperature in the translating devices which are supplied from the circuit. it is a well known fact. that electrical apparatus, in general, is capable of sustaining a considerable overload for a relatively short time without injury, while the continuous application of much smaller electric currents material The circuit of my present invention is reto undetermined values of electric 7 nt truver ing the circuit in which it is connected, but these predetermined values are autmnaticaily adjusted by u thermo-responsive device such that the best possible protection for the circuit may be afforded thout unnecessarily disturbing its contie l of the accompanying drawings is e evatiou of a circuit interrupter conid in accordance with my invention, l l ig 2 is a sectional elevation on the line lii of Fig. 1, which illustrates the construction of the thermo-responsi-fve device constituting a part of the interrupter.

Referring to the drawings, the circuit interrupter here illustrated comprises stationary con-tact members 1 and 2 which are mounted on an insulating slab or base 2*, a movable bridging contact member 8, an opereting handle lever i, a latch 5 and a tripping magnet The tripping magnet comprises a stationary core member 7 and a movable core member 8, the eflective weight of the latter being adjusted. by varyingthe position of a counter-weight 9.

I deem it. unnecessar to describe the circuit interrupter in detai since its structure is shown and described in Patent No. 633,772, granted September 26, 1899, to the Nestinghouse Electric & Manufacturing Gom any,

as assignee of Gilbert Wright and Christian Specification of Letters Patent.

Application filed Kay 6, 1907. Serial No. 872,208.

Iifildltlfi, WILKIll'SE'UIi-G, PENNSYLVANIA, ASSIGNQR T0 VIE$CINGHQUSE LECTRIC & MANUFAGTURXNG CQIEPANY, A CGEPQEATIQN 0 PENNSY'LVdHIA;

ELECTRIC-CIRCUIT INTEERUPTEB,

Patented J uly 12, 1914 Aalborg, and is well known in the art. Fun therrnore, in my present invention, the circuit interrupter illustrated is intended to be indicative of devices of this general class without imposing limitations as to any specific structure. I

The value of electric current which will actuate the circuit interrupter, is dependent upon the efiective weight of the movable core member '8 and also upon thelength of the air gap between the stationary and movable core members; As above indicated, the efi'ective weight or" the movable core member 8 may be adjusted by varying the position of the counter-weight 9 which is mounted on a rocking arm 10. The counter-weight is in the form of a traveling nut and is moved longitudinally with respect to the rocking arm 10 by means eta screw-threaded rod 11', in a weli known manner.

order to provide an automatic adjustment of the air gap between the stationary and movable core members "I and v 8, thoracic-responsive device 12, which cooperates with the interrupter, is mounted on the insulating slab 2-. 'lhis device comprises a supporting bracket 13, e snait will is rotatably mounted in and insulated from. the bracket 13, a pair of thermo-responsive spirals 15, a clevis 16 which is insulated irom the shaft and is stationary reiative thereto, and an adjusting member 1? which is rotatably mounted on and insulatedfrom the shaft i The inner ends of the spirals 15 are filfifibl'ifially connected together by means of the shaft 14 to which they are firmly secured, while their outer extremities are ut lised to terminal'studs 18 which are secured to the insulating slab 2 and may be so connected in circuit that all or a pormachine, while the interrupter is adapted to control the armature circuit of the same machine.

Each of the spirals 1's built up of a plurality of resilient conducting strips having unlike co-eificients of expansion so that variations in temperature cause such a movement of their inner. ends that a rotative movement of the shaft 14 is produced. The clevis 16 is of such shape that it does not interfere with the movement of the spirals and its extremities are provided with holes which engage square shoulders 19 on the shaft 14 bein insulated therefrom by sleeves 20. In t is way, rotative-movements of the shaft roduce corresponding movements of the c evis 16. The adjusting member 17 consists or" two bellcrank levers which are joined together at their extremities to term two U-shaped arms 21 and 22. The arm 21 engages a projection 23 on the movable core member 8 and the arm 22 may be clamped to the clevis 16 bya set-screw 24.

The operation of the device is as follows:

I Assuming that the arm 22 of the adjusting member 17 is clamped to the clevis 16, by means of the set-screw 24, in such position that thearm 21 supports the core "member 8 in position to insure the desired air gap between it and the stationarycore member 7 when no current traverses the circuit intcrrupter; an excessive current or" comparatively brief duration, if suilicient to produce a r'lux corresponding to the width of the air gap and the adjustment of the counter-Weight 9, will cause the core member 8;. to rise and efiect withdrawal oi the latch 55'. a current or a lesser value than that ju'st1 mentioned traverses the circuit fora; sufi-f cient length of time to heat the-spirals l5 and time cause them to expand, they will efiect rotation of the'shatt M and consequent movement of the parts 16 and l? to decrease the width of the air gap between the members 7 and 8, In this way, interruption of the circuit will be efiected by a lesser current traversing the circuit for considerable length of time as well as by a current of greater value continuing for a short time.

By suitable adjustment of the member 17, re ative to the clevis 16 and the position of the counter-weight 9 on the bar 10, the circuit interrupter may be calibrated in accordance with such limiting currents of both long and short duration as may be desired.

1 claim as my invention: a

1. in a circuitinterrupter, the combination with stationary and movable contact members, a latch for holding the members normally in engagement, and a tripping magnet for the latch having a movable core member, of two double-strip current-conducting spira-ls having rigidl mounted outer ends and rigidly connected ut jointly mov-c scares able inner ends, a device for supporting the movable core member in its no-load position, and means for adjustably connecting said device to the inner ends of the spirals.

2. In a circuit interrupter, the combination with stationary and movable contact members, a latch for holding the members in engagement, and a latch tripping magnet having a movable member, of current-conducting spirals having rigidly supported outer ends, a device for supporting the m0v-' able member of the tripping magnet in its no-load position, and an adjustable connection between said supporting device and the inner ends of the spirals.

3. In a circuit interrupter, the combination with stationary and movable contact members, a latch for holding the members in engagement, and a tripping magnet tor the latch having stationary and movable core members, of a current-conducting spiral ha'v ing a rigidly supported-end, a device for supporting t 1e movable core member in its no-load position, and means for making an adjustable connection between said device andthe free end of the spiral.

at. In a circuitinterrupter, the combination with stationary and movable contact members, a latch for holding the members in en a ement and a trio in ma net for the latch having a movable core member, of

a thermo-responsive device comprising electric-current-carryin spirals having stationary ends movaoleends, and means or adjusting the no-load position of said core member,.said means being operatively connected to-the movable ends "of the spirals.

' 5. a circuit interrupter, the combination with stationary and movable contact members, a latch for holding the members in "engagement, and a tripping magnet for the damn having a movable core member, or a thermo-responsiye device comprisin electric-current-carrying spirals having stationary ends and movable ends, a clone opera- 7 tively connected to the movable ends of the spirals, and a member adjustably attached to the clevis'and operated to adjust theposition of said movable core member in accordance with the expansion and contraction of the spirals.

in testimony whereof, I have hereunto subscribed my name this 30th day of April, 1967.

Witnesses:

a. 6. Dow,

Hum". 

